1. Field of the Invention
This invention relates in general to controlling die casting machines. More specifically, this invention relates to controlling a waste shot of a die casting machine, particularly after the machine has been stopped or paused, and upon initial start up of the machine.
2. Description of the Related Art
Die casting machines generally operate in three different modes. These different modes of operation include: "trial shot mode", "waste shot mode" and "normal shot mode".
Normal shot mode: Normal shot mode refers to the normal continuous operation of a die casting machine during which operation it is manufacturing die cast products (as long as the machine is operating normally).
Trial shot mode: A die casting machine is operated in its trial shot mode before it is operated in its normal shot mode. During trial shot mode, the operator establishes the various operating parameters that will be used during normal shot mode operation.
Waste shot mode: Usually the die casting machine is operated in its waste shot mode during warm up. Waste shot operation is usually carried out when the machine is turned on initially, or after it has been paused for sufficient time for the molds to cool to a temperature below that required for normal mode operation.
Once the parameters of normal operation have been established during one or more trial shots, and the die casting machine has been warmed up and operated with one or more waste shots, it can be operated in normal shot mode in accordance with the parameters determined during test shot mode operation to continuously manufacture products.
During normal shot mode operation, the die casting machine is controlled automatically by a control apparatus of the die casting machine. However, normal mode operation of the die casting machine may be stopped for various reasons. For example, the machine operator may take a lunch break, there may be a need to change a damaged mold or change to a next mold, or there may be some unusual occurrence requiring the die casting machine to be stopped.
When the die casting machine stops, the temperature of its metal mold begins to cool. This cooling will continue until the machine is re-started. Accordingly upon re-start of the machine, the operator of the die casting machine must again operate the machine in waste shot mode before he can operate it in normal shot mode.
In known die casting operations, the operator of the die casting machine must re-set operation conditions for waste shot mode operation each time the die casting machine is stopped or paused and the machine is to be operated in waste shot mode. After setting the conditions for waste shot mode operation, the operator then causes the machine to operate in waste shot mode.
Even though the waste shot conditions are already known by the operator, he must manually set them each time before operating the die casting machine in waste shot mode.
Even if the die casting machine is operated automatically, the operator must manually change the operation of the die casting machine from waste shot mode operation to normal shot mode operation. This decreases efficiency.
Moreover, in known die casting arrangements, the die casting machine is sometimes operated in waste shot mode when it is not necessary to do so. Naturally, this reduces efficiency.
Accordingly, it is desirable to provide for more automatic control of a waste shot mode operation of die casting machines It is advantageous to automatically recognize predetermined conditions that are appropriate for waste shot mode operation and to control the die casting machine so as to automatically operate in accordance with those conditions.